Walking Assist Device Pendulum Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing walking assist devices that apply torque to the knee joint without affecting the hip joint struggle to synchronize the swings of the lower leg with the upper leg during the swing phase, especially for users who cannot control their knee joints effectively, and rely on expensive inclination angle sensors for determining target knee joint angles.
Innovation Solution
Incorporating a pendulum at the lower end of the upper link that emulates the motion of the lower leg, with a pendulum sensor to detect its swing angle, allowing the controller to synchronize the lower link's movement with the upper leg's motion, thus guiding the user's leg in a natural walking motion without the need for expensive sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a walking assist device applies torque to the knee joint without affecting the hip joint, then the device structure is simpler, but the synchronization between lower leg and upper leg swings deteriorates
Solution Approach 1:
The patent introduces an intermediary mechanism (pendulum attached to upper link) that mediates between the upper leg motion and lower leg control. The pendulum detects upper leg swing angle and transmits this information to the controller, which then adjusts knee joint torque to achieve synchronized leg swings, resolving the contradiction between simple structure and motion synchronization.
2Measurement precision
If an inclination angle sensor is used to determine target knee joint angle, then the synchronization precision is improved, but the device cost increases
Solution Approach 1:
The patent creates a mechanical copy of the upper leg's angular motion through the pendulum mechanism. Instead of using an expensive inclination angle sensor to directly measure target knee joint angle, the system uses a pendulum that replicates the upper leg's swing characteristics, providing the necessary angular information at lower cost while maintaining synchronization precision.
3Ease of operation
If the device controls only the knee joint without hip joint control, then the ease of operation is improved, but the walking motion naturalness deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the pendulum continuously monitors upper leg swing angle and feeds this information back to the controller. The controller uses this feedback to dynamically adjust knee joint torque, ensuring the lower leg motion naturally follows the upper leg motion pattern, thereby maintaining walking motion naturalness while requiring minimal user control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables low-cost synchronization of the lower leg with the upper leg's motion during the swing phase, mimicking the double pendulum motion to achieve natural and smooth walking, while avoiding the use of costly inclination sensors.
Implementation Method 1
a pendulum (50) which swings around a pitch axis in response to a swing motion of the upper link (14)
Implementation Method 2
a ground reaction force sensor (19) to detect a ground reaction force which is applied to a sole of the user's foot
Data Source
AI summary
A walking assist device which assists the knee joint with well synchronizing with the upper leg motion during the swing phase at low cost may be provided. The walking assist device comprises an upper link, a lower link, a rotary joint, an actuator, and a controller. The upper link is to be attached to an upper leg of a user. The lower link is to be attached to the lower leg of the user. The rotary joint swingably connects the lower link to the upper link. The rotary joint is coaxially aligned with the user's knee joint when the user wears the walking assist device. The actuator swings the lower link relative to the upper link. The controller controls the actuator so that the lower link guides the user's walking motion.